Unified module housing

ABSTRACT

A transmit/receive (T/R) module of a phased array radar having a unified housing comprising an integrated connector as part of the module housing, thereby eliminating a hermetic joint between a group of DC signal pins and the module housing. Power and RF signal connector pins are provided in the housing. The pins of the connectors are inserted within the module housing with a glass compression seal around each pin.

The Government has rights in this invention pursuant to Contract No.DASG60-90-C-0210 awarded by the Department of the Army.

BACKGROUND OF THE INVENTION

The present invention relates to an electronic module and moreparticularly to a unified housing of the module having sidewalls, frontand rear sections fabricated as a single entity with the rear sectionbeing made to form a DC signal connector and to provide connection meansfor a power input and an RF signal input.

A solid state phased array radar system utilizing monolithic microwaveintegrated circuit (MMIC) transmit/receive modules in a phased arrayantenna are generally constructed such that each individual T/R moduleis mechanically fastened to a liquid cooled cold plate which is sized insome multiple of array elements to form an array subassembly or tray.Typical subassemblies may comprise between 32 to 48 elements and areplugged into a backplane which comprises electrical connections as wellas input and output cooling manifold arrangements. Each subassemblyrequires expensive, leakproof, blind-mate, quick disconnect fluidcoupling pairs.

To perform repairs in the field an entire tray subassembly containingmany good modules must be removed, replaced with an all goodsubassembly, and returned to a maintenance facility for replacement ofthe failed module. This scheme forces a very costly spares penalty onany system inasmuch as full trays become the least replaceable unit(LRU).

One prior art approach to T/R module retention is described in U.S. Pat.No. 3,818,386, to Doyle S. Granberry, and assigned to Texas Instruments,Inc. An H shaped plate is used to secure the T/R module in place intheir respective sockets of a support structure. However, the H plate isnot captive to the module and comprises loose parts. Also, DC signalconnection pins are provided at one end wall of the T/R module housing;they extend through a connector block which requires a hermetic seal tothe end wall of the housing.

Another approach to T/R module retention in a phased array radar systemis described in U.S. Pat. No. 4,998,181, to James L. Haws et al. andassigned to Texas Instruments, Inc. An all monolithic round T/R modulewith electrical connectors on an end wall having tiedown/eject screwsattached on the side of and at the antenna end of the T/R module. Thisattachment device is used to affect engagement and disengagement of theelectrical connector by jacking the module in and out of the mainassembly. However, it does not hold the module in intimate contact withthe cooling plate.

It is very desirable to be able to install or remove individual T/Rmodules from the tray using a single tool without the need to remove thetray from the radar antenna subsystem nor any other parts. Thissignificantly reduces system and life cycle costs by allowing individualmodules to become the least replacement unit (LRU) thereby eliminatingextra tray, module, and hardware costs.

In the prior art the methodology of T/R module construction has been toform a metal enclosure with large cutouts for connectors, procurehermetic multipin and RF connectors, and weld or braze them into thehousing. This methodology results in large perimeter hermetic jointswith a potential risk for leakage due to voids in the weld or braze.Rework and scrap costs can be high.

It is very desirable to eliminate as many hermetic interfaces aspossible. The glass compression seal around each pin is a highlyreliable, well understood process that is employed to seal each pin intoa connector. It follows then that if the connector pins are glasseddirectly into the module housing, a very large redundant hermetic jointcan be eliminated. Further, if the interface features of the connectorsare included in the basic housing configuration, the T/R module housingwill now also serve as the connector housing. This results in lowercosts, fewer components, higher reliability and a vastly reduced scraprate.

SUMMARY OF THE INVENTION

Accordingly, it is therefore an object of this invention to provide anelectronic module having a unified housing.

It is also an object of this invention to provide a unified housinghaving integrated connectors for DC signals, a power input and an RFsignal input.

It is a further object of this invention to provide an unified modulehousing that is lower cost and has higher reliability by reducinghermetic joint interfaces.

The object are further accomplished by providing a unified modulehousing comprising means on a first end of the housing for providing asignal connection path, means provided in the first end for inserting amodule retainer means, a second end of the housing comprises a connectorshell formed therein having a plurality of recessed cavities forinsertion of first connector pins, means disposed in the second end ofthe housing for insertion of second connector pins, and a pair ofsidewalls, each of the sidewalls being disposed on a side of the unifiedmodule housing normal to the first end and the second end. The unifiedmodule housing comprises a nickel iron alloy. The housing comprises apair of ramps formed in the housing, each of the ramps being disposed oneach side of the second end of the housing for providing a hold downforce when the module housing is inserted into a mating assembly tray.The second connector pins means comprises means for providing a powerinput. Also the second connector pins means comprises means forproviding a path for an RF signal. The module retainer means comprises atubular assembly disposed in the unified module housing having an offsetinner diameter, a helical groove provided in a first portion of thetubular assembly, means disposed in an end of a second portion of thetubular assembly for inserting a tool to rotate the tubular assembly, astud assembly disposed in each module location of the tray, acylindrical hole in the tray at each module location for insertion ofthe tubular assembly of the module housing, and the stud assemblycomprises a ball stud protruding into the cylindrical hole of the trayand engaging the helical groove of the tubular assembly of the modulehousing wherein a rotation of the tubular assembly translates intolinear motions in two orthogonal directions causing the module to beretained in the tray. The linear motions in two orthogonal directionscomprises a first motion along a longitudinal axis of the assembly forinserting a connector of the module housing into a tray connector and asecond motion orthogonal to the longitudinal motion for moving themodule housing into forced contact with the tray. The first motion andthe second motion in two orthogonal directions occur simultaneously. Theoffset of the inner diameter determines an amount of orthogonaltranslation of the module for bringing the module housing into contactwith the tray. The helical groove provides for appropriately 180°rotation of the tubular assembly.

The objects are further accomplished by providing a microwave modulecomprising a unified housing, a first end of the unified housing havingat least one cavity for insertion of means for providing a signalconnection path, the first end comprises a recessed cavity for insertionof a module retainer means, a second end of the unified housingcomprises a connector shell formed therein having a plurality ofrecessed cavities for insertion of hermetic sealed connector pins,cavity means disposed in the second end of the housing for insertion ofhermetic sealed RF signal and power connector means, a pair of sidewallseach one being disposed on a side of the unified housing normal to thefirst end and the second end, a base plate disposed on edges of thesidewalls and mating with the first end and the second end in a mannerto provide a hermetic seal, a septum means disposed between the firstend and the second end of the housing separating the module into twochannels, a circuit board disposed in each channel of the module havingelectrical connections to the connector pins on the second end, antennameans for each of the two channels attached to the first end of thehousing and being electrically connected to the corresponding circuitboard, and cover means attached on a top surface of the module in amanner to provide a hermetic seal. The unified housing comprises anickel iron alloy. The unified housing comprises a pair of ramps formedin the housing, each of the ramps being disposed on each side of thesecond end of the housing for providing a hold down force when thehousing is inserted into a mating assembly tray. The module comprises asignal distribution means coupled to the connector pins of the secondend of the housing for distributing signals to the circuit board in eachof the two channels.

The objects are further accomplished by a method of providing a unifiedmodule housing comprising the steps of providing a signal connectionpath means on a first end of the housing, inserting a module retainermeans in a recessed cavity of the first end, forming in a second end ofthe housing a connector shell having a plurality of cavities forinsertion of first connection pins, providing cavity means in the secondend of the housing for insertion of second connector pins for a powerinput and an RF signal, and providing a pair of sidewalls, each of thesidewalls being disposed on a side of the unified module housing normalto the first end and the second end. The method comprises the step offabricating the unified module housing with a nickel iron alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

Other and further features and advantages of the invention will becomeapparent in connection with the accompanying drawings wherein:

FIG. 1 is an exploded isometric view of the invention comprising atubular cam assembly portion and a stud assembly portion;

FIG. 2 is a perspective view of an subassembly tray having a pluralityof modules connected therein showing an exploded view of a trayconnector plate, and a removed dual channel T/R module comprising atubular cam assembly portion of the invention, and it also shows a toolfor insertion and removal of the T/R module to and from the subassemblytray;

FIG. 3 is an isometric view of the tubular cam assembly showing ahelical groove, a retaining set screw and a tool slot in a head of thecam assembly.

FIG. 4 is an isometric view of a portion of a subassembly tray having aT/R module removed and showing a cut away of a stud assembly portion ofthe invention;

FIG. 5 is a top view of a tubular cam assembly;

FIG. 6 is an end view of the tubular cam assembly of FIG. 5 at the endwhere an insertion tool is inserted;

FIG. 7 is a sectional view of the tubular cam assembly takensubstantially on lines 7--7 of FIG. 5 showing a cut-out for a retainingset screw that also provides for a 180° rotation of the cam assembly;

FIG. 8 is an end view of the tubular cam assembly of FIG. 5 at thehelical cam end showing the offset inner diameter;

FIG. 9 is an isometric view of a dual channel T/R module having aunified housing with electronics circuit boards included therein; and

FIG. 10 is an isometric view of a connector end of the T/R module ofFIG. 9 showing the utilization of the module housing as the connectorbody, DC and RF pins hermetically sealed in the housing, and hold downramps.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 and FIG. 2, FIG. 1 shows an exploded isometric viewof the invention of a dual action module retention apparatus 10comprising a tubular cam assembly 12 and a stud assembly 14. FIG. 2shows a dual channel T/R module 52 comprising the tubular cam assembly12 disposed therein and a subassembly tray 60 with the stud assembly 14disposed therein, and such tray 60 in the preferred embodiment comprisesa cold plate 62. In a phased array radar antenna comprising a pluralityof trays 60 having in each of the trays 60 a plurality oftransmit/receive (T/R) modules 52, this invention permits individual T/Rmodules 52 to be installed and removed in and from a subassembly tray 60with a single tool 50. The tool 50 is used for inserting the module 52into a subassembly tray 60. An exploded view of a connector plate 64 ofthe subassembly tray 60 is shown having a connector 66 for each module52 inserted into the tray 60. A cover plate 68 is attached over theconnector plate 64.

Referring now to FIG. 1 and FIG. 3, FIG. 1 shows an isometric view ofthe tubular cam assembly 12, and FIG. 3 is an isometric view of thetubular cam assembly 12 disposed in an end of the T/R module 52. Thetubular cam assembly 12 comprises a helical groove 28, a retaining setscrew 34, a tool slot 38 in an end of the tubular cam assembly 12, andthe tool 50. The tool 50 which has a roll pin forming a "T" shape isinserted into the head of tubular cam assembly 12 in order to insert themodule 52 into the tray 60. A set screw 34 is inserted into the module52 and extends into a slot 36 in the body of the tubular cam assembly 12for locking the tubular cam assembly 12 to the module 52. The end of theset screw protrudes into slot 36 of the tubular cam assembly 12 allowingrotation of the tubular cam assembly 12, but at the same time preventingaxial motion of the tubular cam assembly 12.

Referring to FIG. 1, FIG. 2 and FIG. 3, the tubular cam assembly 12comprises a helical groove 28 formed in its body to provide an axialtranslation of 0.180 inches in the present embodiment when the tubularcam assembly 12 is rotated 180° in order to engage connector pins at themodule 52 in a mating tray connector 66. A required contact forcebetween the module 52 and tray 60 is determined by thermal analysis, andin the present embodiment such force is 54 pounds. This contact force isprovided by the tubular cam assembly 12 by compressing the conicalwasher 46 between an upper flange portion of a nut retainer 42 and aninner surface of the tray 60. The tubular cam assembly 12 is captivatedin the module housing by the set screw 34 to prevent unwanted axialmotion relative to the module housing. A detent is machined into the endof the helical groove 28 which in conjunction with a compliant thrustwasher on the cam screw 34 provides a lockout of the module.

Referring now to FIG. 1 and FIG. 4, FIG. 1 shows an exploded view of thestud assembly 14, and FIG. 4 is an isometric view of a portion of thesubassembly tray 60 having a T/R module 52 removed showing a cut away ofthe stud assembly 14 disposed in the tray 60. The stud assembly 14comprises a cylindrical nut retainer 42 having a circular flange 41 atapproximately the center of the nut retainer 42. A conical washer isdisposed over an upper portion of the nut retainer 42 resting on theflange 41. A threaded ball stud 44 is screwed into the upper end of thenut retainer 42. A retaining ring 40 is inserted around a lower portionof the nut retainer 42 to secure it in the tray 50. An adjustment hole63 is provided in the tray 60 above the location of the stud assembly 14to allow for adjustment of the height of the ball stud 44. A cylindricalhole 61 is provided for insertion of the tubular cam assembly 12disposed in a module 52. The ball stud 44 extends into the cylindricalhole 61 and when a T/R module 52 is inserted, the ball stud 44 engageswith the helical groove 28 of the tubular cam assembly 12 wherein arotation of the tubular assembly 12 translates into linear motion in twoorthogonal directions causing the module 52 to be retained in the tray60. A first motion along a longitudinal axis of the tubular cam assembly12 provides for inserting a module connector 54 into a tray connector66, and a second motion orthogonal to the longitudinal motion providesfor moving the module 52 into forced contact with the tray 60. Both ofthese motions occur simultaneously.

Referring now to FIG. 5 and FIG. 6, FIG. 5 is a top view of the tubularcam assembly 12. The head 18 of the tubular cam assembly 12 comprises anopening for insertion of the tool 50. FIG. 6 is an end view of the head18 showing the opening for the tool 50 and a recessed channel 19 withinthe head 18 for rotating the tool for removal of the T/R module 52 fromthe tray 60. At the other end of the tubular cam assembly 12 is thehelical groove 28. "A" represents the width of the helical groove 28which is just slightly wider than the body of the ball stud 44. "B"represents the outside diameter of the tubular cam assembly 12 which isslightly smaller than a hole in the front face of module 52 into whichthe tubular assembly 12 is disposed. "C" represents the distance alongthe longitudinal axis that the tubular cam assembly 12 must move, whichin the present embodiment is 0.180 inches, in order to have the pins ofthe module 52 properly inserted into the tray connector.

Referring to FIG. 3, FIG. 5 and FIG. 7, FIG. 7 is a sectional view ofthe tubular cam assembly 12 taken substantially on lines 7--7 of FIG. 5at the point where the slot 36 is provided for insertion of the setscrew 34. This slot 36 provides the limits for the 180° rotation inconjunction with the set screw.

Referring to FIG. 1, FIG. 5 and FIG. 8, FIG. 8 shows an end view of theinner diameter and outer diameter of the tubular cam assembly 12 whichare offset and configured such that rotation about the longitudinal axiswhile engaging in the helical groove 28 a stud assembly 14 disposed in atray 60 produces a translation of motion in a plane orthogonal to thelongitudinal axis of the tubular cam assembly 12. As noted above theamount of motion along the longitudinal axis is determined by therequired amount of engagement for the module electrical connector 54 andit is controlled by the length of the helical grove 28 in the tubularcam assembly 12. The contact force between the module 52 and thesubassembly tray 60 is determined by the size, quantity and type of theconical washer 46. The module retention apparatus 10 of FIG. 1translates a singular rotational motion into simultaneous straight linemotions in two orthogonal directions.

Referring to FIG. 2, FIG. 3 and FIG. 9, FIG. 9 shows two monolithicmicrowave integrated (MMIC) circuit boards 78, 79 which are packaged ina unified housing 53 of module 52. The DC signal connector 54 end of themodule 52 comprises two wedges 56, 58 disposed on each side of thesignal connector 54; an RF connector 76 is disposed under the firstwedge 56 and a DC power connector 74 is disposed under the second wedge58 structure (see FIG. 10). The tubular cam assembly 12 having a tooloperated actuation is located at the end of the module 52 having theantenna radiators 85, 86. During installation of the module 52 into thesubassembly tray 60, the tubular cam assembly 12 translates the module52 into a mating tray connector 66 and mating wedge structures 70, 72 oneach side of the tray connector 66 as shown in FIG. 2, whilesimultaneously locking the module 52 in place by applying compressiveforces that press the base of module 52 at the antenna radiator end ofthe module 52 against the cold plate 62 of the tray 60. The wedgestructures 70, 72 of the connector plate 64 force the base of module 52at the connector 54 end of the module 52 against the cold plate 62 asthe module connectors 54, 74, 76 mate with corresponding connectors onthe connector plates 64. The helical groove 28 of the tubular camassembly 12 fits over the neck of the ball stud 44 during module 52installation and forces the antenna radiator end of the module 52against the cold plate 62 of tray 60 in accordance with forces providedby compressing the conical spring washer 46.

Still referring to FIG. 9, the unified housing 53 of dual channel T/Rmodule 52 is generally rectangular shaped and comprises two sidewalls, arear end where connectors 54, 74, 76 are located and a front end wherethe tubular cam assembly 12 and antenna radiators 85, 86 are located.The antenna radiators 85, 86 may be embodied with quartz windows. Theunified housing 53 is fabricated from nickel iron alloy material by ametal injection molding (MIM) process readily known in the art. Theconnector 54 end of the unified housing 53 includes all of the featuresnecessary to provide DC power, RF and DC signal connectors. The frontend of the housing 53 has surfaces for mounting the antenna radiators85, 86. Two holes (not shown) are provided behind each antenna radiator85, 86 for making the electrical connections from the MMIC boards 78,79. The number of such holes is dependent on a particular application.An interface ceramic substrate 51 distributes signals such as fromconnector pins 59 to the MMIC boards 78, 79, in each channel and thesubstrate 51 comprises single layer or multilayer printed circuitscommonly known in the art. The material for the unified housing 53 isselected to provide an optimum thermal coefficient of expansion (TCE)match between a sealing glass around each connector pin and acopper-molybdenum (C_(u) M_(o)) alloy material for the housing base 88.The MIM process is a cost-effective methodology for providing largequantities of housings as are required in a phased array antenna. Itwould be obvious to one of ordinary skill in the art that otherprocesses such as machining could be used to fabricate the unifiedhousing 53. The connector pins are high temperature glass sealed intothe nickel-iron alloy housing 53. Subsequently, the C_(u) M_(o) base 88is brazed to a bottom surface of the housing 53, and the quartz windows,antenna radiators 85, 86 are brazed to the front end of the housing 53;the assembly is then leak tested. Each T/R module channel comprises aMMIC board 78, 79 which comprises a plurality of microwave components 80on an alumina thin film network 82 assembled onto a C_(u) M_(o) carrierplate 84. A septum 87 made of C_(u) M_(o) alloy material is positionedbetween the two channels of MMIC boards 78, 79 to provide electricalisolation between the two T/R module channels; the septum 87 may bebrazed or soldered in place or secured with conductive epoxy. Theelectronics of the MMIC boards 78, 79 are tested after assembly into theunified housing 53, and then a cover is seam sealed to a top surface ofthe housing 53 creating a hermetic module 52. A helium leak test isperformed on the module 52 to determine the adequacy of its level ofhermeticity.

Referring now to FIG. 10, an isometric view of the rear end of theunified housing 53 shows the utilization of the unified housing 53 asthe body or protective shell of connector 54. Also, the connectors 74,76 for the DC power pin 55 and RF signal pin 57 respectively are formedin the housing 53 using the housing 53 as their outer protective shell.The DC signal pins 59 are glass sealed at high temperatures into thehousing 53. Also shown are the hold down ramps 56, 58, the DC power pin55 and the RF signal pin 57 which are also glass sealed into the housing53.

This concludes the description of the preferred embodiment. However,many modifications and alterations will be obvious to one of ordinaryskill in the art without departing from the spirit and scope of theinventive concept. For example, the unified module housing 53 may beconfigured to have connectors formed on more than one side of thehousing for other applications. Therefore, it is intended that the scopeof this invention be limited only by the appended claims.

What is claimed is:
 1. A unified module housing comprising:means forattaching a radiator on a first end of said housing to generate radiofrequency energy; means provided in said first end for inserting amodule retainer means; a second end of said housing comprises anintegral connector shell formed within said second end having aplurality of recessed cavities for insertion of first connector pins;means disposed in said second end of said housing for insertion ofsecond connector pins; and a pair of sidewalls, each of said sidewallsbeing disposed on a side of said unified module housing normal to saidfirst end and said second end.
 2. The unified module housing as recitedin claim 1 wherein:said unified module housing comprises a nickel ironalloy.
 3. The unified module housing as recited in claim 1 wherein saidhousing comprises a pair of ramps formed in said housing, each of saidramps being disposed on each side of said second end of said housing forproviding a hold down force when said module housing is inserted into amating assembly tray.
 4. The unified module housing as recited in claim1 wherein:said second connector pins means comprises means for providinga power input.
 5. The unified module housing as recited in claim 1wherein:said second connector pins means comprises means for providing apath for an RF signal.
 6. The unified module housing as recited in claim3 wherein said module retainer means comprises:a tubular assemblydisposed in said unified module housing having an offset inner diameter;a helical groove provided in a first portion of said tubular assembly;means disposed in an end of a second portion of said tubular assemblyfor inserting a tool to rotate said tubular assembly; a stud assemblydisposed in each module location of said tray; a cylindrical hole insaid tray at each module location for insertion of said tubular assemblyof said module housing; and said stud assembly comprises a ball studprotruding into said cylindrical hole of said tray and engaging saidhelical groove of said tubular assembly of said module housing wherein arotation of said tubular assembly translates into linear motions in twoorthogonal directions causing said module to be retained in said tray.7. The apparatus as recited in claim 6 wherein said offset of said innerdiameter determines an amount of orthogonal translation of said modulefor bringing said module housing into contact with said tray.
 8. Theapparatus as recited in claim 6 wherein said helical groove provides forappropriately 180° rotation of said tubular assembly.
 9. The apparatusas recited in claim 6 wherein said tool inserting means in an end ofsaid second portion of said tubular assembly comprises recessed meansfor locking said tool to enable removal of said module from said tray.10. The apparatus as recited in claim 6 wherein said stud assemblycomprises:a nut retainer; a conical washer disposed between an upperportion of said nut retainer and an inner surface area of said tray;said ball stud being screwed into said nut retainer; and a retainingring means inserted around a lower portion of said nut retainer.
 11. Theapparatus as recited in claim 10 wherein a compression of said conicalwasher provides a pull down force for holding said module in contactwith said tray.
 12. The apparatus as recited in claim 10 wherein saidtray comprises an adjustment hole above a location of said ball stud toenable adjustment of the height of said ball stud into said cylindricalhole.
 13. The apparatus as recited in claim 6 wherein said linearmotions in two orthogonal directions comprises a first motion along alongitudinal axis of said assembly for inserting a connector of saidmodule housing into a tray connector and a second motion orthogonal tosaid longitudinal motion for moving said module housing into forcedcontact with said tray.
 14. The apparatus as recited in claim 13 whereinsaid first motion and said second motion in two orthogonal directionsoccur simultaneously.
 15. A microwave module comprising:a unifiedhousing; a first end of said unified housing having at least one cavityfor insertion of means for providing a signal connection path; saidfirst end comprises a recessed cavity for insertion of a module retainermeans; a second end of said unified housing comprises a connector shellformed therein having a plurality of recessed cavities for insertion ofhermetic sealed connector pins; cavity means disposed in said second endof said housing for insertion of hermetic sealed RF signal and powerconnector means; a pair of sidewalls each one being disposed on a sideof said unified housing normal to said first end and said second end; abase plate disposed on edges of said sidewalls and mating with saidfirst end and said second end in a manner to provide a hermetic seal; aseptum means disposed between said first end and said second end of saidhousing separating said module into two channels; a circuit boarddisposed in each channel of said module having electrical connections tosaid connector pins on said second end; antenna means for each of saidtwo channels attached to said first end of said housing and beingelectrically connected to said corresponding circuit board; and covermeans attached on a top surface of said module in a manner to provide ahermetic seal.
 16. The microwave module as recited in claim 15wherein:said unified housing comprises a nickel iron alloy.
 17. Themicrowave module as recited in claim 15 wherein said unified housingcomprises a pair of ramps formed in said housing, each of said rampsbeing disposed on each side of said second end of said housing forproviding a hold down force when said housing is inserted into a matingassembly tray.
 18. The microwave module as recited in claim 15wherein:said module comprises a signal distribution means coupled tosaid connector pins of said second end of said housing for distributingsignals to said circuit board in each of said two channels.
 19. A methodof providing a unified module housing comprising the steps of:providingmeans for attaching a radiator on a first end of said housing togenerate radio frequency energy; inserting a module retainer means in arecessed cavity of said first end; forming within a second end of saidhousing an integral connector shell having a plurality of cavities forinsertion of first connection pins; providing cavity means in saidsecond end of said housing for insertion of second connector pins for apower input and an RF signal; and providing a pair of sidewalls, each ofsaid sidewalls being disposed on a side of said unified module housingnormal to said first end and said second end.
 20. The method as recitedin claim 19 wherein said method comprises the step of fabricating saidunified module housing with a nickel iron alloy.